HVAC has always been a hobby of mine.  But I work in the computer industry (after leaving the automotive repair industry after 15 years).

I am researching putting a Geothermal system in my home, and have a couple questions.

Home: Location = Honey Brook PA (SE PA)
1200 sq foot rancher 20 years old. Current heating plant only heats main home.
1/3 of the basement (walkout) is finished. That finished basement room is heated by Pellet stove.  Heat rises through a 6' opening that contains spiral stairs to main home.

Current system:
Hamilton Home Products (york) air to air 3 ton 10 seer heat pump.  (this is the pre charged system with sealed lines that have threaded (instead of solder) ends that have the puncture seal a home owner (me) can install with out a Freon license.

Backup Oil Heat (independent oil burner with its own air handler, using same duct work)

Thermostat (honeywell vision pro) does the fossil fuel kit with external temp sensor and switches to oil from heat pump and oil at 25deg F.
When it switches from HP to oil, the HP fan cuts off and the oil furnace blower fan is controlled by heat of oil furnace air box.
Currently 100 gallons of heating oil last 2 to 3 years.

I also have a large wood furnace (Jensen) that has its own air handler fan.  This system is hooked up to duct system. When I put thermostat in Emergency Heat mode, it controls a fan that blows air into the fire box on the wood stove to stoke fire and generate heat. as stove temp rises, sensors in the wood furnance turns on the fan to blow air through ducts (much like how an oil heater works).  
I have the AC/Heatpump coil mounted on top of the Jensen furnace with the Honeywell thermostat controling the Woodstove fan as the air handler for the AC/Heat pump coil.  winter 800 CFM. Summer Stage 1 800 CFM, stage 2 1000 CFM (stage 2 only speeds up the fan).

Thermostat Set temps We run:
Winter 65 during the day (everyone is away) and 68 in morning and evening, then 66 at night.  Weekends 68 all day, 66 at night.
Summer 75 evenings, 74 night, 78 daytime (everyone is away during day) Weekends 75 all day, 74 at night.

Next step, Geothermal:
The current 3 ton heat pump is getting old (10 years) and I want to replace it before it starts to cost money for repairs. (and PECO electric rates keep going up and up).  Based on the performance history of the current 3 ton system, I am going to replace it with a new 3 ton system (although more efficient)

Geothermal system:
I am leaning towards the ClimateMaster Tranquility 30 Digital (TE) series with the Hot water generator, and no backup electric heat.

Closed Ground Loops:
I have talked to several local installers about sizing my ground loops.  I was leaning heavy towards horizontal loops (because I have excavators in the family) until I realized the place they would need to be installed is the only backup location for a new on lot septic system if it were required in the future.  So I will go with vertical loops.

I already have one 280' water well that is no longer being used for drinking water since we switched over to city water.  The local well driller (who does a lot of geothermal in my area) offered to come in and drill a 2nd well, Remove well pump from original well,  install 250' of 1.25" loop in each well, pressure test, seal the wells, then plumb it back to the house through the basement wall for around $3K.  I need to see if he will also flush the lines for me.

Flow Center:
I am still deciding between using the ClimateMaster built-in Vflow system or the B&D mfd QT-2 (2 pump) flow center.  Sales/technical literature pushes me more towards the additional energy savings of the Vflow system.

DIY Install.
I will pickup and install the TEV038 unit on high density pad, install required duct system extension and duct for return air. Wire everything including ATC32U01 thermostat (including external temp sensor) and do plumping.  Then I need to hire someone to come in and do the startup.


My few questions:
Is there anyway to configure the Climate master to turn off, and switch over to the oil furnace when it gets real cold? (like what a fossil fuel kit does)
both fans running is way too much volume for the duct work.
Or I could just switch off the Geothermal system and turn on separate thermostat for the oil burner on those few nights its real cold if needed.

I realize I will also have to run a separate thermostat for the wood stove, (then turn the Geothermal system to off while burning wood).
But to be honest, there are a lot of cons with the wood stove (smell, cutting and splitting wood) and I might just remove it since I only use it 2-3 weeks per winter.

Does anything jump out here as a mistake, or even a "your crazy"?

Thanks for your time reading this.

Just to clarify one thing in the above. The pellet stove in the finished room in the basement is only used when we are in that room, which is not very often.
I use at the most 15 bags of pellets per year. Mostly over Christmas time because the tree is in that room .

It sounds like you are into this thing up to your neck - that's cool

Several things

1) Get or do a load calc - 3 tons sounds heavy for the size of house and climate. Seek ways to cut the design load down toward two tons - air leaks or insulation. Have a competent energy auditor in to have a look, including a blower doo whole house infiltration test. Make it a room-by-room load calculation.

1a) Don't base anticipated performance of a 3 ton geo heat pump on the present performance of a 3 ton air source heat pump. ASHPs are rated at 47*F outside, and capacity falls rapidly with outdoor temperature. Consider air flow testing of the present system. National data suggests existing systems deliver less than 60% of rated capacity owing to insufficient airflow. At minimum, have someone check TESP across the air handler...better yet a flow hood test of every supply register / grill compared with results of room-by-room load calc described above.

1b) You MIGHT be able to skip well #2 with a 2 ton solution, which should save big bucks, though I'll defer to the local pros on that one. There is design software for that...ensure it gets used.

2) Run the numbers for losing the oil in favor of electric resistance. Oil steady state combustion efficiency is at best 85%, but I'd be willing to bet yours delivers 60% or less owing to short cycling and standby losses. Aux heat might only cost 50-100 per year to run and you'd lose all the complexity of the oil system...you DO have a tank leakage insurance policy covering spill cleanup, right?

I used to live in PECO service territory and hated writing them checks, but oil is a really pricey source of heat and given world wide demand for Diesel fuel, it is hard to imagine heating oil ever dropping much in price in the way natural gas has.

3) Thinking a bit further out of the box, run the numbers for a Carrier GreenSpeed air source heat pump. Consider also a minisplit heat pump for the downstairs room. Some minisplits deliver 100% of rated heating capacity down to 10*F or so, and 80% at -4*F...amazing performance.

Thanks for the reply Curt.

1) I have a pro who lives up the street I was just talking to. He can do #1. We are planning on meeting soon. Best part is his house is very much like mine (and he has Geo).  If the home is almost identical, we might be able to use the calculations he did for his house.

I did have one local installer tell me my current well "should" support 2.5 Ton.

2) removing the oil has been in my thoughts as well. Its old(er) and don't owe me anything. But if it quits, I will be wishing I had the electric backup. The electric heater is in the estimate I received. I have enough electric service to support it: 200 amp and 100 amp (100 amp used to be Off peak but PECO got rid of off peak and residential heat rates 1/1/13).
The heater coil is cheep enough I will probably buy it anyway.

3) The downstairs room hardly gets used during the winter. When we do use it in the winter the pellet stove heats it up quick, plus adds atmosphere .

I can post back here as I gain data and do the install.

Good - keep us up to date.

All else is speculation until you know the homes requirements.

one of my problems is my requirements change. When my Daughter is home from Collage, I turn the duct on within her room.
When someone is in the guest bedroom, I turn the duct on in that room.

Even the walkout basement room (that has the pellet stove) has ducts, but I never turn them on.

That doesn't change my earlier stance...toggling the register slats in the odd room now and then has little or no impact on system design. if a couple extra rooms are being heated and cooled, system will work a little harder and / or call for aux heat for a few extra minutes now and then...no worries.

When a room you describe is not conditioned it likely runs no more than 5 or so degees above / below the rest of the house, so impact on whole house heating and cooling load is quite small.

"one of my problems is my requirements change."
Not so. Your behavior might change but the home's heat loss/gain does not.
If you are going to over-complicate the simple manual J load for your home a DIY geo project will no doubt be quite a challange.
j

Here are some residential Heat loss and heat gain calculations using HVAC-Calc.
(in accordance with ACCA Manual J)

Just the main level of the home, the area I currently heat and cool.
total Heat Gain (BTUH) 17,398
Total Heat Loss (BTUH) 25,017.

Now if I include the basement room (which Now I heat with a pellet stove when we want to use the room in winter, and its 3 sides under ground with 2" x 6" framed wall that is exposed to outside, so it stays cool in summer).
Total Heat gain 20,277
Total heat Loss 29,149.

Now how do you apply these numbers to a Geothermal Heat pump?

Are these numbers what the heat gain and loss would be as an average based on average temps for my area? or the max numbers needed based on my expected High and Low outside temps?

looking at the climate master documentation, I see the following for ground loop heat pump

TE-026 model
Cooling capacity BTUH
Part 20,900
full 26,300
Heating capacity BTUH
part 15,300
full 18,900

Cooling: Meets my requirements on part load.
Heating: I need to find 10249 more BTUH. I think I only need to add a 3.8KW heater for 13,000 BTU. (estimate has 10KW heater on it).

TE-038 model
Cooling capacity BTUH
Part 30,400
full 39,900
Heating capcity BTUH
part 23,200
full 29,200

Cooling: 10K more cooling then I need on part load.
Heating: meets my load on full.

If I continue to use my pellet stove in the basement room when I am in there, the TE-026 almost meets my heat load without electric.

Am I doing this correct?

You are on a right track. A 2 ton might get small quickly. Don't skip out the supplement heat.

Currently I have one 265' depth well that i will be switching over to GEO. (500' loop of 1.25" pipe in well) plus another 100' of line (8' below grade) because well is 50' from house.
total of 600'. also still need to figure really what size pipe fits the requirements. All I am going on is the well driller said "everybody around here uses 1.25" pipe".

It sounds like that single well will support a 2 ton unit, but a 2 ton unit will not support the house for heat. By changing my lower design temperature in the software, I see the 2 ton unit running on stage 2 will support the home at 22 deg. F. Honestly I only see around 2 weeks per year that the temps go below that number, then that is at night when the thermostat currently gets set back to 65 deg. one school of thoughts is the savings of not adding the 2nd well will pay for a lot of electric heat when the temps do go below 22 Deg F.

I also understand a 2 ton unit will not work as well to do the 2 deg recovery when the thermostat goes back to 68 for day time.

I need to look at a 2.5 ton specs to see if it will have enough heat. But not sure my well above will support 2.5 ton.

right now it's looking like I should just spend the extra bucks, drill the 2nd well, buy the 3 ton system, and be happy (hopefully for the next 20 years) and electric heat might never even come on.

How much water is in that well? How far down to the water level? Is it cased? If so, with what material and to what depth?

Would it be possible to hook up a very small pump with some 1/2" pipe to the bottom of the well and bleed off ~2-3 gpm while the heat pump is running?  If so, that fresh water makeup to the well would go a long way in extending your heating capacity.

Well is cased with steel, probably 60 foot? (what ever is normal for a drinking well). Water is within 15' of top. When drilled, they said "we can only measure 10 gallons per minute, and your way over that".

But there is a superfund site within 1/2 mile (that's why they hooked me up to city water). the aquifer actually goes the other direction from my well (mine has always tested clean), but If I suck water out of the well (more then say washing a car or watering the grass), I could spread the contaminates from the super fund site over my directions. they have several test wells setup (in fact they were using mine as a test well). they would know it if I started to spread the contaminates.

But what was the number, "5 gallons per foot"?  so there is at least 1200 gallons in reserve.
Plus the board of health wants me to grout the well when I switch over to Geo. This way they can mark my well as "closed" and remove it from the tracking database.

I just DIY'ed my geothermal, and something I did might have application for you. The incremental cost of the 3 ton versus the 2.5 ton is not large, so I would be tempted to just go ahead and get the larger one that looks like it can do your load. That is much cheaper then deciding that you need it later. With regard to the well, the incremental cost is large, so I would be tempted to just use the well as is and see if you have an under capacity issue. That is one advantage for the DIY: you can take a wait and see approach to the problem, the reputable professional needs the numbers to work ahead of time.

For my system we back filled the field in November, and then had the coldest December in over a decade, so my field didn't have the time to settle before I asked full capacity from it. Needless to say I overran my field. What I did is add an additional sensor to the LWT (anded with the heat call) which turns on the backup heat if the field temperature drops, assisting the heat pump, reducing the demand on the field, and stabilizing the field temperature . That first season I really needed it, this season not so much, although last month when we spent a week below design temperature it did kick on. Doing something like this would let you install the heat pump with the current well and see if the system has enough capacity without the risk of low temperature shutdown. You might find that the current well has enough capacity, or, if not, you can make an informed decision if the best solution is more well, or insulation, or just live with some backup heat cost.

I'm gonna stick to my guns as to a 2 ton solution. Having a system oversized for summer cooling will extract penalties in both efficiency and comfort (poor dehumidification)

Don't be afraid of a few dozen hours of aux operation.

I'm willing to bet that pellet stove outputs way more than the incremental heating load added by the basement in the calculation.

Since you have so much water in the well and it provides such good heat transfer, have you considered back-filling with pea gravel up to within ~20' of the surface and then filling the remainder with cement grout after the geothermal pipes are installed?

What is the temperature of your well water? What temperature does the geothermal heat pump use to determine heating capacity? Your entering water temperature should be pretty close to your deep well water temperature. You may have more heating capacity margin here than you think.

Another idea is to install the 2 ton geothermal with your existing well with electric resistance backup heat. If you find that isn't enough capacity, supplement it later on with a small (9000 - 12000 BTU) high efficiency mini-split heat pump heating the basement area as needed. Another advantage of this option is that the mini-split can be used to dehumidify the basement in summer.

Good Question Arkie6. I think "law" requires me to grout the whole wall...

But I always heard that water cools your body 25 times faster then air. I don't know how water compares to grout for conducting temperature from a Geo loop.

Visiting your load calcs:
"Are these numbers what the heat gain and loss would be as an average based on average temps for my area? or the max numbers needed based on my expected High and Low outside temps?"

These are max based on 20 year average.

"If I continue to use my pellet stove in the basement room when I am in there, the TE-026 almost meets my heat load without electric.

Am I doing this correct? "

Yes vs other helpful do it yourself designs, the most efficient systems aim for the lions share of the load with geo and the extreme loads with auxiliary. This is truly more efficient than a bigger compressor all the time vs a little auxiliary every now and again.
You can use electric resistance or pellet stove auxiliary.

You can also mitigate some load to reduce auxiliary requirements.

Engineer, The more I learn, I more I am starting to "see the light" in your guidance .

After talking with an experienced local designer, and using another software package this installer recommended named GeoDesigner I have come up with the following information:

With the 2 ton unit, it will be 11 deg before Aux electric heat will start to come into play (as long as I don't do temp offset swings higher then Aux stage is set for).

Using my true electric rates, Geodesigner shows around $24.00 more per year for heat with a 2 ton VS a 3 ton.
But because the 2 ton runs longer, it heats more hot water, which lowers my hot water costs by $12.00 per year.

Savings: There is around $1K different in unit prices, plus the 2 ton can run with a one 250' loop in my existing well. Plus my inlet pipes run 75' between the house and well at around 6'-8' deep. I will separate the pipes to add a little more Geo heating/cooling to the total loop.
Not having to drill that 2nd well will save around another $2000.00. (Still waiting on the price to just put a loop in my current well, grout the well, and run pipes to the house).

They are still recommending 1.25" pipe. The guy who installs the loop pipe is willing to come back later the fill the system (flush cart) with water using methanol antifreeze

Instead of an external flow center, at this point I will probably go with the system that uses internal variable speed pumps controlled by the ECM in the Geo unit.

$3000 saved Divided by the additional $12.00 cost per year to run the 2 ton = 250 years
Plus I already know the AC will actual work better on the 2 ton (and I bet cooling will hardly ever go past the 1st stage).

Edit:  This above figure is using the Geo system to heat the same space I currently heat (just the home, not the basement).   
I will continue to use the pellet stove when I want to occupy the finished basement room.  I can also use the pellet stove to offset the heat when its real cold out and I bet I might never see the electric heat come on.